Periodicity of a class of nonautonomous max-type difference equations

In this note we prove several general and easily applicable results regarding the periodicity of positive solutions of the following difference equationsxn=max{f1(xn-k1,n),…,fm(xn-km,n),xn-s},n∈N0,andxn=minf1(xn-k1,n),…,fm(xn-km,n),xn-s,n∈N0,where 1⩽k1<⋯